1. Field of the Invention
The present invention relates to an image reproducing system such as a copying apparatus, a document reader, a printer and so on.
2. Description of the Prior Art
As an example, a color reproducing printer using a photosensitive drum is explained in the following.
The printer is such a type of apparatus that processes color signals of B, G and R to control a laser beam from each latent color image of Y, M, C and BK on the photosensitive drum, develops the latent image by each developer of Y, M, C and transfers the color image on a transfer paper to form a color image. In this case, the color image quality is apt to deteriorate due to fatigue or lapse of time. Consequently, unreasonably frequent maintenance service may be required.
So far a copy registration (alignment) has been usually performed by adjusting the starting timing of light beam irradiation to the drum or by adjusting the timing of transfer paper feed while observing a reproduced image of a test sample original.
Also each balance adjustment has been performed by means of adjusting the voltage applied to the charging electrode while observing the reproduced image. As an example, FIG. 9 shows a reproduced image of the test chart as illustrated in FIG. 8. This is the case where the R image shifts to the lower right and further the image density of the R image is higher. In such case, however, if the reading unit and the image reproducing unit are separated by a long distance from each other, such as being located in different buildings, the above-mentioned adjustments have been difficult.